All campaign rallies have been banned in Kinshasa, the capital of the Democratic Republic of Congo, for security reasons ahead of Sunday's presidential election.
The city's governor, Mr Andre Kimbuta - who is a member of the ruling party - said he had received information that what he called "extremists" from the camps of all the presidential candidates were planning a confrontation in the streets.
One of the opposition candidates, Mr Martin Fayulu, hit out at the move.
His team said authorities were trying to stop him from campaigning.
With President Joseph Kabila due to step down, this election is the first time the country is changing its leadership via a vote since independence - previous transitions of power have all been violent.
President Kabila's favoured successor is Emmanuel Ramazani Shadary, his former Interior minister.
His strongest rivals are Mr Fayulu and Mr Felix Tshisekedi.
Kinshasa is considered an opposition stronghold.